4 Answers
4

General

Re-balanced XP. The amount of XP to gain levels has been re-adjusted to better mesh with the character wealth by level charts (e.g. Starting gold vs 13.33 encounters of thr appropriate CR's worth of treasure). This means that after 5th level, it requires more than 1000 * level to get the next level. There are also fast and slow XP charts now (x2/3 and x4/3 required/level).

Combat Maneuvers. Trip, sunder, etc. have been re-balanced into combat maneuvers that utilize a Combat Maneuver base (usually the same a BAB). When trying to trip a person, you make a Combat Maneuver Attack vs that persons Combat Maneuver Defense. This works like attack vs AC. It's a much improved system and the Advanced Player's Guide [APG] adds some additional maneuvers. So far the combat maneuvers are: trip, sunder, grapple, bull rush, disarm, overrun, drag (pulls a creature), reposition (relocates a creature within your reach), dirty trick (applies short-term conditions), steal (snatches objects from the target).

Favored Class. No XP penalty for multiclassing, but a level in your favored class is worth 1 hp or 1 skill point. The APG has additional options based on class and race. E.g.: an half-orc sorcerer may choose to get +1/2 point of damage to fire spells (rounded down). That is, if he chooses this options for two levels, he gets a net +1 damage with fire damage spells.

Encounter Level. Better rules for determining CR. Each monster is worth a fixed XP amount to be divided evenly among players. Allows for fine tuning of encounters.

Feats

Are granted at every odd level.

Feats like Power Attack are now less flexible but simpler and with better value. Deadly Aim has been introduced to provide the same Power Attack feature with ranged weapons.

Cleave is far less circumstantial and became a separate exploit.

There are no/fewer dead feats. Toughness gives +1 hp per level (and the first 3 hps are granted upfront at 1st level) so it's useful. Dodge is a plain +1 dodge AC versus all opponents. Skill augmenting feats (like Alertness or Animal Affinity) give +2 to a couple of skills but improve to a +4 if you have 10 ranks in that skill.

Skill System

Some skills have been aggregated. Relevant examples are Perception and Stealth.

There is no 1st-level x4-kicker: if you are a Rogue you get (8 + Int modifier) skill points per level. So a 1st level, non-human Rogue with Int 10 has exactly 8 skill points (or 9 if Rogue is her favorite class and she chooses to invest there). This is balanced by the fact that if you have at least one rank in a class skill you get a +3 bonus in that skill.

There are no 1/2 ranks. Spending a skill point in cross-class skills gives you a full rank (but you don't get the +3 bonus).

Permanent modification to your Intelligence score may cause you to lose or gain skill points.

Half-Orc. +2 one ability score. +2 to Intimidate. One last round as disabled when brought below 0 hit points.

Human. +2 one ability score.

Classes

More Options. Most classes have a list of specific class features from which you can cherry-pick from (like the 3.5e's Rogue talent, but much more varied and awarded starting at much lower levels). Expect more diverse characters.

Class Features. All class features' save DCs goes up with level (10 + 1/2 class level + ability mod.). Monster's saves are not generally sky-high, so the features have a chance to connect.

Very Few Dead Levels. Most empty lines in the class tables have been filled up with something. Some full casters (Clerics, Sorcerers and Wizards) still have levels where the only new feature is a new spell slot.

Caster Level. All caster classes have caster level equal to their level.

Cantrips and Orisons. 0-level spells now are more like at-will abilities. Wizards/Clerics/Druids memorize them as normal, but casting them doesn't make the caster forget the spell. Sorcerers have infinite 0th level slots but limited known.

Hit Dice. Some classes have been promoted (bolded, below)

d12: Barbarian

d10: Fighter, Paladin, Ranger

d8: Bard, Cleric, Druid, Monk, Rogue

d6: Sorcerer, Wizard

One Level Dipping A 1 level dip in most classes is less useful than it used to be. Many of the features have been spread across multiple levels or are based on class levels.

20th Level Capstone. A class specific, powerful ability only is only available at 20th level. Since PF does not have epic-rules yet (not that these are hard to import), single-classing is sexier than before.

No Multiclass Penalty. Paladin and Monk restrictions are a thing of the past. XP penalties are gone too.

Barbarian

Rage. More flexible: counted in rounds per day, rather than times per day.

Bard

Bardic Performance. Better/more clear rules on types of performances that count for bardic performance. Expanded list of performances; some of them escalate with level. Deadly performance as 20th level capstone. The Perform skill ranks requirement has been dropped.

Versatile Performance. For a Bard, each Perform skill can act as a double for two other skills (e.g.: Perform (Act) can be used in place of a Bluff or Disguise check, Perform (Percussion) in place of a Handle Animal or Intimidate check). This does not mean he has to actually play an instrument, but simply that he can use the skill bonus of another skill.

A Knack with Skills. Bards have diverse new features that interact with skills. From being able to ignore the trained requisite, gaining all skills as class skills, and taking 10 even when not allowed, up to taking 20 on Knowledge checks up to 3 times per day.

Good Feat Support. Arcane Strike and other feats allow a Bard to become much more effective in armed combat. So you're not dead weight or a fifth wheel.

Cleric

Proficiency. They are no longer proficient with heavy armor.

Domain Powers. Increased in power and have level-dependent effects (usually a second ability that kicks in at 6-8th). The most frequent powers granted at 1st level are touch or range attacks that deal about 1d6 + 1/2 cleric level. The benefit of +1 to caster level on related spells is no longer a given.

Channel Energy. The old turn/rebuke became a 30 ft. burst of positive or negative energy that heals or inflicts 1d6/odd level damage to nearby creatures. Feats allow you to selectively exclude targets. Channel feats as normal (but the list of feats is pretty different). Turn and rebuke are not a default for Clerics; they have to acquire the relevant feat.

Druid

Wild Shape. Awarded earlier and its usages per day go up more frequently. At 20th level Druids can wild shape at will. All shapechange spells are more precise in what abilities you gain. Physical stats of the wild shape comes as a bonus to character's ones: not as a replacement. This goes along with a complete overhaul of the form-shifting spells.

Animal Companion. Can be substituted for access to a Cleric domain (and domain spells) chosen among Air, Animal, Earth, Fire, Plant, Water, and Weather. The animal companion option, however, is pretty good.

Fighter

Retraining. At 4th and every other 4th level thereafter, a fighter can trade out a bonus feat he has for a new one as long that old feat isn't being used as a prerequisite.

Bravery. A bonus to Will saves vs fear that goes up with level.

Weapon Training. Bonuses on weapon groups (a +1 to attack and damage that goes up to +4 at 17th level). Additional weapon group training is awarded later with decreasing bonuses (like the Ranger's favored enemy). At 20th chooses a weapon and gain +1 to critical multiplier, automatic threat confirmation and immunity to disarm with that weapon.

Monk

Flurry of Blows. Treated as two weapon fighting with no off hand and BAB equal to Monk level instead of 3/4 level. At 20th his flurry breakdown is +18/+18/+13/+13/+8/+8/+3. Can use combat maneuvers instead of attacks with a CMA equal to the above BAB.

Bonus Feats. Awarded at 1st, 2nd, 6th, 10th, 14th, and 18th from a custom list (narrower than the Fighter's one).

Ki Pool. Is a set of ki points that increase with level. Ki points could be expended for additional attacks or temporary bonus to AC, and later to fuel supernatural abilities such as incredible jumps, self-healing, dimension door or etherealness.

Paladin

Channel Energy. As a good Cleric, but relies on Lay on Hands uses instead.

Smite Evil. Lasts the entire fight, provides a bonus to AC too, and hurts evil dragons and evil outsiders more. Up to 7 times per day at 19th.

Divine Bond. Either a special mount or a holy spirit that inhabit and buffs the Paladin's weapon.

Lay on Hands. Numbered uses per day that increase with level. Each use cures 1d6/odd level. Standard action on others, free action on self.

Spells. Now are Charisma-based; Wisdom is no longer a favorite ability for Paladins.

Holy Champion. At 20th level Paladin heals maximum amount of damage (60) with Lay on Hands or Channel Energy, and Smite Evil banishes the target if it is an evil outsider.

Ranger

HD: d10.

Favored Enemy. The granted bonus to damage is not precision-based (it is meaningful against creatures immune to critical hits and at any range).

Combat Style. At 2nd, 6th, 10th, 14th and 18th picks a bonus feat from a list that is tied to the chosen style. Styles are two-weapon combat or archery; APG adds crossbow, mounted combat, natural weapon, two-handed weapon, and weapon and shield.

Hunter's Bond. Either an animal companion (which is no longer a worse version of the Druid's) or the ability to grant allies half the Ranger's damage and to hit bonus vs favored enemies.

Quarry. Select a designated foe. Can track at full speed and gets extra combat bonus against.

Favored Terrain. Can select favored terrains (such as forest, cold, urban, underground, etc.) that grant bonuses on initiative and some skills. Up to 4 terrain types at 18th level.

Master Hunter. 20th level capstone feature grants a possible death attack once per day against each favored enemy type (doesn't matter if the target is quarry or not).

Rogue

HD: d8.

Rogue Talent. Every even level they can cherry pick a rogue-specific trick. Talents are divided in normal (2nd to 8th) and advanced (10th to 20th). Many of these talents kick in when applying sneak attack damage.

Trapfinding. A plain +1/2 level to Perception and Disable Device skill checks relating to traps. They also can disable magic traps.

Trap Sense. An increasing dodge bonus (up to +6) to AC and Reflex against trap attacks.

Sorcerer

HD: d6.

Bloodline. Sorcerers select a bloodline at 1st level (like arcane, draconic, fey, etc.). Each bloodline provides 5 powers (including the 20th level capstone), a list of spells that are automatically added to the Sorcerer's repertoire, and a knack with certain kind of spells.

No Familiar. Except for the arcane bloodline.

Wizard

HD: d6.

Arcane Bond. Either a familiar or a bonded object (ring, wand, staff, etc.). The object allows casting of a spell in spellbook 1/day even if you haven't memorized it.

Arcane School. A specialist Wizard must use two slots to memorize a spell from an opposed school (select two). Each specialization brings two additional abilities at 1st level, plus another that kicks in at 6th or 8th. Universalist Wizards also gain one ability at 1st level (a minor telekinesis) and the ability to apply a metamagic feat on a spell on the fly at 8th.

Alternate Race Traits. Trade off base racial traits with new ones (of the same race). Examples: dwarven Hatred trait (bonuses against orcs and goblinoids) can be traded for the Ancient Enemy trait (bonuses against drow), halfling Keen Senses can be traded for Low Blow (+1 on critical confirmation rolls against target larger than themselves), human bonus skill points can be traded for Heart of the Streets (+1 to Reflex and AC when adjacent to at least 2 allies, and crowds are not difficult terrain for them).

Alternate Kits. Trade off a set of base class features with a set of new ones (of the same class). Examples: archer fighter, cloistered cleric, scout rogue, scroll scholar wizard, hospitaler paladin, arcane duelist bard.

Traits. Mini-feats (e.g.: +1 to hit when in surprise round) that are more often story hooks than abilities (in general 2 at first level).

Hero Points. Rare points that allow for astonishing effects (stave off a spell for 1 round, perform an additional action, reroll a crucial die, etc.). Collected at level up and as additional rewards from the GM.

Teamwork Feats. Great bonuses that only apply if your friends also have them.

What this Means

More power. Characters' power level has been tuned up. In particular, they seems to be more resilient.

Item creation changes. Expect your players to actually use these feats now. You wizard will craft wands, etc. and will make items for 1/2 price. Be prepared to deal with it.

Combat Maneuvers. Expect people, Monks especially, to opt for tripping/grappling etc. since it's worth it now and is much easier to calculate.

Sorcerer, Monk, Fighter fixes. People may stick with these classes since they don't suck anymore.

Capstone abilities. Alternatively, no multclassing since 20th level ability is so nice for each class.

Animal Sidekick alternative. No more useless mount/animal companion if you run primarily dungeon crawls.

Shape change. GM's life is easier. Harder to dump physical stats. No more CoDZilla.

Channel Energy. This will come into play a lot more. Clerics can heal a large number of people using this ability. So can Paladins. They can also burn a large number of zombies. Plan accordingly.

Paizo has managed to take virtually every aspect of 3.0/3.5 and tweak/rewrite it to work faster and be more balanced. They managed to bring choice and variation of abilities to every single class (some more than others, still). With the Advanced Player's Guide they introduce 6 classes that are all balanced and playable with the 11 core classes, giving 17 core classes.

So why do Elves suffer -2 Con instead of -2 Str? Elves shouldn't be frail - they can live hundreds of years, only need 4 hours of rest per day, and are more resilient than humans (at least in Tolkien's works they are nearly immune to disease and hunger).
–
RobertFNov 14 '13 at 15:07

3

@RobertF Probably because the core races that get penalties to strength are all small. Plus, strength penalties make for fairly bad warriors of any type: even archers. Additionally, D&D hasn't been LotR: The RPG for a few decades now and Pathfinder has it's own, anime influenced, world and design. So dragging Tolkien into it makes as much sense as pulling soccer rules into a discussion on football.
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KitsuneYMGSep 26 '14 at 7:59

Is it just me or the half-elf seems way better than the human?
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Matteo TassinariOct 23 '14 at 20:11

@MatteoTassinari It's just you, IMO. half elf has a few tricks they can do (Paragon Surge until your DM bans it), but bonus feat is hard to compete with. The ACF to get 3 skill focus feats or a second +2 is pretty hardcore
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KitsuneYMGOct 23 '14 at 20:20

Races have all been powered up; +2 to two stats, -2 to one stat (including half-orcs!), with some different abilities for some. In 3.5 terms, they're roughly an ECL of +1 (as opposed to 0 in 3e).

No one has a favored class decided by their race now - you choose your favored class, typically the one you level at 1st level, but you don't get an XP penalty for multiclassing too high above that one - you just gain an extra skill point or hit point for leveling your favored class.

Many of the classes have had options added, often to fill out "dead levels." Barbarians gain extra "rage powers," sorcerers have bloodlines that give them granted powers, wizards have varying effects for specializing, fighters get more than just bonus feats, undead-turning is actually energy channeling and also results in an AOE heal, and so on.

Classes have some sort of awesome power at 20th level, encouraging single-classing as a valid option.

Complex combat maneuvers and defenses against them have been boiled down to two numbers: Combat Maneuver Attack bonus and Combat Maneuver Defense.

Skills have also been altered and consolidated. Instead of Hide and Move Silently, there's now just Stealth. Instead of Listen, Spot, and Search, there's simply Perception. Gather information has been absorbed into Diplomacy.